a. Field of the Invention
The present invention relates to foil fences for hydrofoil craft utilizing the submerged foil system and in particular to the hydrofoil craft having the "canard" foil arrangement.
B. Description of the Prior Art
The utilization of perpendicularly oriented fences at a foil tip has been tested and resulted in a reduction of drag especially in the take-off period of the hydrofoil craft.
Foil fences for the purpose of improving speed and preventing vortex development at the foil tip and for improving the lift distribution of the foil have not been observed in the hydrofoil art. The closest approach was noted only in the similarity of structure where the use of perpendicularly oriented stabilizing fins was shown, such as in the U.S. Patents Nos:
3,183,871 PA1 3,425,383 PA1 3,635,035 PA1 3,688,723 PA1 1. canard, PA1 2. airplane, and PA1 3. tandem arrangement.
However, the stated purpose for the fin structure of these patents is that of stabilization only and not drag reduction and/or improvement of lift distribution.
The closest approach to the present invention of using a fence or fin on a foil or wing-tip for vortex influence control was noted in the aircraft prior art, in U.S. Pat. Nos. 2,576,981 and 3,152,775.